Abrasive wheel



Feb 6, 1951 G. J. GOEPFERT rs1-Al. 2,540,112

ABRASIVE WHEEL Filed Dec. 29, 1949 INVENTOR. GEORGE J GOEPFERT BY OU/5L. COI-'PAN Patented Feb. 6, 1951 STATES, PATENT ortica ABRASIVE WHEELGeorge J. Goepfert and Louis L. Cofran, Niagara Falls, N. Y., assignorsto The Carborundnm Company, Niagara Falls. N. Y., a corporation ofDelaware Application December 29, 1949, Serial No. 135,691

10 Claims. (Cl. 51206) are often used for dressing operations in thefinishing of metal articles, grinding out fillets and the like, althoughdue to their thinness they can also be used for cutting-off purposes.

The present invention is especially adapted to A abrasive wheel.

body of the wheel at the time that it is formed two or more sheets orplies of suitable nonabrasive fabric. Most satisfactory results havebeen obtained by using a resin-impregnated woven fabric which ispreferably placed in from, but adjacent to, each flat side surface ofthe In other words, although the impact strength of an abrasive Wheel,such as a thin cut-oil wheel, composed of abrasive-included fibrousmaterial is increased by placing the woven fabric plies within the wheeleither adjacent the sides of the wheel or in more nearly the centerportion laterally of the wheel, the flexural abrasive cutting-off wheelsand wheels of similar structure and will therefore be primarilydescribed as it pertains to such wheels although it is pointed out thatit is also applicable to other types of grinding wheels wherein thegrinding is performed at or on the periphery of the wheel.

Conventional cut-off wheels of the prior art are usually composed ofabrasive grains held together by a suitable resinous or rubber bond.They are used at high speeds ofirevolution but in order to'provide therequisite hardness to produce a fast and cool cutting rate withoutexcessive wheel wear the bond is necessarily cured or vulcanized to anextremely hard condition. As a result the abrasive Wheels so made are ofvery low exural strength so that wheel breakage frequently occurs whenth-` wheel is subjected to the least lateral stress or impact with notonly loss of the wheel before it has served its useful life but withconsiderable danger to the operator. This deficiency in impact and/orflexural strengths has never been satisfactorily overcome.

It is an object of the present invention to provide an abrasive wheelhaving a satisfactory performance life and an acceptable high cuttingrate.

It is a further object to provide an abrasive wheel which notonly has asatisfactory life and cutting rate but also is of high impact andflexural strengths.

Other objects and advantages accruing from the practice of the presentinvention will become apparent as the description proceeds.

We have found that abrasive wheels with satisfactory life and cuttingrate, having high impact and flexural strengths, can be made by formingthe wheels of a felted fibrous abrasivecontaining material and embeddingwithin the strength of such a wheel is not greatly improved unless thewoven fabric layers are positioned in from, but in the vicinity of, thetwo wheel sides. The fabric to be selected for promoting the impact andflexural strengths by embodiment within the wheel should be of suchcharacter that the edges of the fabric at the periphery of the wheelwill break down during the operation of the wheel without smearing orotherwise interfering with the grinding or cutting function. At the sametime the fabric must have a durability and strength of its own suihcientto impart to the wheel the desired increase in both impact and flexuralstrengths. Such a combination of functions is most readily obtained byusing a fabric which has been impregnated with a heathardenable resin.We have found a woven fabric such as a canvas, duck, or drill clothimpregnated with a phenolic condensation product resin to be highlysatisfactory for the purpose.

A uniform thickness of the thin side layers of abrasive-included fibrousmaterial forming the two dat side surfaces of the wheel, as well as auniform thickness and density of the main body portion ofabrasive-included brous material is best obtained by using anabrasive-included fibrous material in the form of thin sheets or pliescut to the shape of thin circular discs. The number of plies used foreach side surface section, as well as for the central body portion, ofthe wheel will depend largely upon the thickness of wheel desired.

One abrasive-containing brous material which has been found highlysuitable for making abrasive wheels in accordance with the presentinvention is the abrasive-included felted fibrous sheet materialdisclosed and fully described in U. S. Patents Nos. 2,284,738 and2,284,739. In making an abrasive wheel such as an abrasive cutting-offwheel using the sheet material of the above patent the sheet material isdied, punched or otherwise cut out in the form of a number of circulardiscs of a diameter slightly greater than vthe diameter of the wheel tobe made. The sheet material either before or after it is cut to thisform is sized with a suitable combining adhesive which is allowed to dryto a substantially nontacky condition in which it is suitable forhandling. One or more discs of the abrasive-containing felted fibroussheet material are placed on the bottom mold plunger in a molding press,and superposed by a disc-shaped sheet of the chosen fabric. Theabrasive-containing sheet material which is to make up most of theabrasive wheel body structure is then placed upon the fabric sheet,after which a second fabric sheet similar to the irst sheet of fabric issuperimposed on the pile of material, followed finally by one or moreadditional layers of the abrasive-containing felted fibrous sheetmaterial. The entire assembly after alignment is then subjected to heatand pressure sufficient to compact and unite the various plies ofmaterial. the compacted wheel shape removed from the mold, and dressedif necessary, after which it is ready for use. If desired, the wheel canbe formed by either a hot or cold pressing operation, followed by curingat a temperature and time suillcient to finally cure or mature thecombining adhesive of the wheel structure.

In order to better understand the nature of the abrasive articles withwhich we are here concerned, reference is made to the accompanyingdrawing showing specific examples of abrasive wheels made in accordancewith the present invention, and in which:

Figure 1 is a top plan view of an abrasive cutof! wheel made inaccordance with the present invention;

Figure 2 is a highly enlarged sectional view through the line 2--2 ofFigure 1; and

Figure 3 is a view, similar to that shown in Figure 2, of a modifiedform of abrasive wheel made in accordance with the present invention.

The exact manner in which abrasive wheels can be easily and economicallymade following the teachings of the present invention is most easilydemonstrated by the following examples setting forth specific proceduresfor the making of illustrative abrasive products.

Eample I Abrasive cut-oil wheels 16" in diameter and in thickness havinga 1" arbor hole have been made as follows: An abrasive-containing feltedfibrous sheet material of the type described in U. S. Patents Nos.2,284,738 and 2,284,739 and composed of a felted cotton fiber base sheetheld together by a casein adhesive and containing approximately 85-90%by weight of 24 grit size aluminum oxide abrasive grain is ilrst sizedon one side with a thin sizing coat o f liquid phenolic resin preparedfrom the reaction product of 1 mole of phenol and from 1.1 to 2 moles offormaldehyde, said reaction being catalyzed by the addition of analkaline catalyst, and the resin dried to a non-tacky condition. Anumber of circular discs 16%" in diameter having centrally located arborholes 1l in diameter are punched out of the sized abrasive-containingbrous sheet material. One disc of the abrasive-included fibrous sheetmaterial is placed on a 16%" diameter steel wheel mold plunger of theconventional type after which a disc-shaped sheet of resinimpregnatedwoven fabric of the same diameter is placed on the mold plunger on topof the single dien nf nhrn giundnn'lnn hmnn chant mnhn'lnl One materialwhich has been satisfactorily used for this purpose is a bluecottondrill impregnated with a phenolic condensation product resin such asthat obtained from the reaction of 1 mole of phenol with 1.5 moles offormaldehyde in the presence of a small amount of an organic primaryamine catalyst. Ten layers of abrasive-included felted ilbrous sheetmaterial the same as that first placed on the mold plunger are thenplaced on top of the resin-impregnated fabric, followed by a singleadditional layer of resin-impregnated fabric which is topped in turn bya final single layer of the abrasive-included fibrous sheet material.The top mold plunger is then placed upon the assembled sheet materialand the entire assembly axially aligned and pressed at 4000 pounds persquare inch pressure at a temperature of 300 F. for 15 minutes. Thethusly molded wheel is then removed from the press, dressed to size inaccordance with conventional procedures, after which it is ready foruse.

Referring further to Figures 1 and 2 of the drawing, which illustrate anabrasive cut-oil.' wheel such as that made in accordance with Example Iabove, the abrasive wheel 4 having an arbor hole 5 is composed ofabrasive-included felted fibrous sheet material 6 and two sheets 1 ofresin-impregnated woven fabric, the woven fabric layers 1 being locatedwithin the wheel adjacent the nat side faces 8 and 9 of the wheelalthough they do not constitute the flat surfaces of the wheel sincethey are faced in each instance by surface layers 6a and 6b of theabrasiveincluded gelted fibrous sheet material. It is noted that thethickness of the wheel as depicted in Figure 2 of the drawing has beengreatly exaggerated in order to bring out more clearly the structuralmake-up of the wheel.

A cut-off wheel of the described type has been demonstrated to have ahighly satisfactory performance life and a high cutting rate. At thesame time a cut-oil wheel of the described type having two layers ofresin-impregnated woven fabric adjacent the side faces of the wheel asshown in Figure 2 has been found to have a flexural strength as much as35-40% greater than the strength of similar laminated abrasive cut-of!wheels in which the resin-impregnated fabric layers have been omitted.As an example of the extremely high flexural strengths obtainable inwheels made in accordance with the present invention abrasive cut-oil.'wheels of the type hereinabove described have been subjected to agrinding test in which the wheels have been used to cut directly into apiece of solid brass rod 2" in diameter to a depth of more than 1"whereupon the brass rod without removal of the wheel is turned laterallythrough an angle as high as 45 in each direction. Abrasive wheels of thepresent invention when subjected to such punishment, cut wedge-shapedsections out of the bram rod without breakage of the abrasive wheel.Conventional resin bonded or rubber bonded cutoi! wheels of the samediameter and thickness, and also abrasive cut-off wheels of similar sizecomposed of abrasive-included fibrous sheet material in which the pliesof resin-impregnated fabric have been omitted, when subjected to thesame test failed to stand up, usually shattering with explosiveviolence. The ability of the wheels of the present invention to resistbreakage or damage under the severe conditions of such a test underwhich other wheels generally fail is adramatic demonstration of theirmarked 'I material compressed and adhesively united, said wheel havingembedded therein at least two layers of resin-impregnated woven fabricsubstantially coextensive in area with the flat side area of said wheel.

2. An abrasive cut-oif wheel composed of a body of abrasive-containingfelted fibrous material and having a layer of woven fabric substantiallycoextensive in area with the flat side of the wheel embedded within butadjacent to each flat side surface thereof.

3. An abrasive cut-oi! wheel composed of a body of abrasive-containingfelted fibrous material and having. a layer of resin-impregnated wovenfabric substantially coextensive in area with the fiat side of the wheelembedded within but adjacent to each flat side surface thereof.

4. An abrasive cut-off wheel conforming to claim 3 in which theimpregnating resin is a resinous phenolic condensation product.

5. An abrasive wheel comprising in the following order from one flatside to the opposing fiat side: a thin layer of abrasive-containingfelted brous material, a layer of resin-impregnated woven fibrousmaterial, a plurality of layers of abrasive-containing felted fibrousmaterial, a layer of resin-impregnated woven fibrous material, and alayer of abrasive-containing felted fibrous material, all said layersbeing compressed together and adhesively united.

6. An abrasive cut-off wheel composed of a body of abrasive-containingfelted fibrous material and having at least one layer ofresin-impregnated non-abrasive fabric substantially coextensive in areawith the at side of the wheel embedded within but adjacent to eachflatside surface thereof.

7. An abrasive cut-olf wheel comprising a plurality ofabrasive-containing felted fibrous sheets composed essentially ofabrasive grains. felted fibers and binder. said sheets of abrasivematerial being compressed and adhesively united. said wheel containingwithin the body thereof adjacent each flat side at least one layer ofresinimpregnated non-abrasive fibrous material substantially coextensivein area with the side area of said wheel.

8. An abrasive wheel comprising in the following order from one flatside to the opposing flat side: at least 1 sheet of abrasive-containingfelted nbrous material, at least 1 sheet of resinimpregnated wovenfibrous material, a plurality of layers of abrasive-containing feltedfibrous material. at least l sheetof resin-impregnated woven fibrousmaterial, and at least 1 sheet of abrasive-containing felted fibrousmaterial, all said layers being compressed together and adhesivelyunited.

9. An abrasive cut-off wheel composed of a body of abrasive-containingfelted fibrous material and having a layer of resin-impregnatednon-abrasive fabric substantially coextensive in area with the flat sideof the wheel embedded within but adjacent to each flat side surfacethereof.

10. An abrasive wheel comprising a plurality of thin felted,abrasive-containing layers of fibrous material compressed and adhesivelyunited, said wheel having embedded therein at least one sheet ofresin-impregnated woven fabric adjacent each fiat side of the wheel.

GEORGE J. GOEPFERT. LOUIS L. COFRAN.

No references cited.

1. AN ABRASIVE WHEEL COMPRISING A PLURALITY OF THIN FELTED,ABRASIVE-CONTAINING LAYERS OF FIBROUS MATERIAL COMPRESSED AND ADHESIVELYUNITED, SAID WHEEL HAVING EMBEDDED THEREIN AT LEAST TWO LAYERS OFRESIN-IMPREGNATED WOVEN FABRIC SUBSTANTIALLY COEXTENSIVE IN AREA WITHTHE FLAT SIDE AREA OF SAID WHEEL.